2021 tax rate fixes and tests

src/forms/Y2021/data/federal.ts

@@ -1,7 +1,7 @@
 import { FilingStatus } from 'ustaxes/core/data'
 import { linear, Piecewise } from 'ustaxes/core/util'
 
-export const CURRENT_YEAR = 2020
+export const CURRENT_YEAR = 2021
 
 interface TaggedAmount {
  name: string

src/forms/Y2021/irsForms/TaxTable.ts

@@ -16,13 +16,35 @@ const computeTax =
  } else if (high === undefined) {
  // This is the top bracket
  return Math.max(0, income - low) * rate
- } else if (income > high) {
+ } else if (income >= high) {
  // Taxable income is above the top of this bracket
  // so add the max tax for this bracket
  return (high - low) * rate
  }
  // Otherwise max income is inside this bracket,
  // add the tax on the amount falling in this bracket
+
+ if (income < 5) {
+ return 0
+ }
+ // If income is between $5 and $25, tax table computes rate at midpoint of $5 ranges
+ if (income >= 5 && income < 25) {
+ income = Math.floor(income)
+ const over5 = income % 5
+ income += 2.5 - over5
+ }
+ // If income is between $25 and $3,000, tax table computes rate at midpoint of $25 ranges
+ else if (income >= 25 && income < 3000) {
+ income = Math.floor(income)
+ const over25 = income % 25
+ income += 12.5 - over25
+ }
+ // If income is between $3,000 and $100,000, tax table computes rate at midpoint of $50 ranges
+ else if (income >= 3000 && income < 100000) {
+ income = Math.floor(income)
+ const over50 = income % 50
+ income += 25 - over50
+ }
  return (income - low) * rate
  }
  )

src/forms/Y2021/tests/f6251.test.ts

@@ -68,8 +68,8 @@ describe('AMT', () => {
  expect(f6251.isNeeded()).toEqual(true)
  expect(Math.round(f6251.l1() ?? 0)).toEqual(87450)
  expect(Math.round(f6251.l7() ?? 0)).toEqual(32864)
- expect(Math.round(f6251.l10())).toEqual(15009)
- expect(Math.round(f6251.l11())).toEqual(17855)
+ expect(Math.round(f6251.l10())).toEqual(15015)
+ expect(Math.round(f6251.l11())).toEqual(17849)
  })
 
  it('small stock options should NOT trigger AMT', () => {
@@ -81,7 +81,7 @@ describe('AMT', () => {
  expect(f6251.isNeeded()).toEqual(false)
  expect(Math.round(f6251.l1() ?? 0)).toEqual(87450)
  expect(Math.round(f6251.l7() ?? 0)).toEqual(7124)
- expect(Math.round(f6251.l10())).toEqual(15009)
+ expect(Math.round(f6251.l10())).toEqual(15015)
  expect(Math.round(f6251.l11())).toEqual(0)
  })
 })

src/forms/Y2021/tests/taxRates.test.ts

@@ -0,0 +1,135 @@
+import { FilingStatus } from 'ustaxes/core/data'
+import { CURRENT_YEAR } from '../data/federal'
+import { computeOrdinaryTax } from '../irsForms/TaxTable'
+import fs from 'fs/promises'
+import { parseCsv } from 'ustaxes/data/csvImport'
+import { parseFormNumber } from 'ustaxes/core/util'
+
+async function getTaxTable() {
+ const path = './src/forms/Y2021/tests/taxTable.csv'
+ const taxTableCsv = (await fs.readFile(path)).toString('utf-8')
+ const rows: Array<number[]> = []
+ await parseCsv(taxTableCsv, (r: string[]) => {
+ rows.push(r.map((s) => parseFormNumber(s) ?? 0))
+ return []
+ })
+
+ // Remove heading row
+ rows.shift()
+
+ return rows
+}
+
+function expectTax(status: FilingStatus, amount: number, tax: number) {
+ const computedTax = Math.round(computeOrdinaryTax(status, amount))
+ // Add a prefix so it's easy to see which one was wrong
+ const prefix = 'Tax on ' + amount + ' = '
+ expect(prefix + computedTax).toEqual(prefix + tax)
+}
+
+function expectTaxUnder100KRange(
+ status: FilingStatus,
+ min: number,
+ max: number,
+ tax: number
+) {
+ const diff = max - min
+ const quarter = Math.round((diff / 4) * 100) / 100
+ expectTax(status, min, tax)
+ expectTax(status, min + quarter, tax)
+ expectTax(status, min + 2 * quarter, tax)
+ expectTax(status, min + 3 * quarter, tax)
+ expectTax(status, max, tax)
+}
+
+describe('Tax rates', () => {
+ it('test should be updated for new year', async () => {
+ // WARNING! Do not just change the year. Also update the CSV and expected tax amounts below!
+ expect(CURRENT_YEAR).toEqual(2021)
+ })
+ it('ordinary taxes for single status should be correct', async () => {
+ const rows = await getTaxTable()
+ rows.forEach(([min, lessThan, tax]) => {
+ expectTaxUnder100KRange(FilingStatus.S, min, lessThan - 0.01, tax)
+ })
+
+ // Over $100,000
+ const amounts = [
+ [100000, 18021],
+ [164925, 33603],
+ [164926, 33603],
+ [209425, 47843],
+ [209426, 47843],
+ [523600, 157804],
+ [523601, 157805]
+ ]
+ amounts.forEach(([amount, tax]) => {
+ expectTax(FilingStatus.S, amount, tax)
+ })
+ })
+
+ it('ordinary taxes for married filing jointly status should be correct', async () => {
+ const rows = await getTaxTable()
+ rows.forEach(([min, lessThan, , tax]) => {
+ expectTaxUnder100KRange(FilingStatus.MFJ, min, lessThan - 0.01, tax)
+ })
+
+ // Over $100,000
+ const amounts = [
+ [100000, 13497],
+ [172750, 29502],
+ [172751, 29502],
+ [329850, 67206],
+ [329851, 67206],
+ [418850, 95686],
+ [418851, 95686],
+ [628300, 168994],
+ [628301, 168994]
+ ]
+ amounts.forEach(([amount, tax]) => {
+ expectTax(FilingStatus.MFJ, amount, tax)
+ })
+ })
+
+ it('ordinary taxes for married filing separately status should be correct', async () => {
+ const rows = await getTaxTable()
+ rows.forEach(([min, lessThan, , , tax]) => {
+ expectTaxUnder100KRange(FilingStatus.MFS, min, lessThan - 0.01, tax)
+ })
+
+ // Over $100,000
+ const amounts = [
+ [100000, 18021],
+ [164925, 33603],
+ [164926, 33603],
+ [209425, 47843],
+ [209426, 47843],
+ [314150, 84497],
+ [314151, 84497]
+ ]
+ amounts.forEach(([amount, tax]) => {
+ expectTax(FilingStatus.MFS, amount, tax)
+ })
+ })
+
+ it('ordinary taxes for head of household status should be correct', async () => {
+ const rows = await getTaxTable()
+ rows.forEach(([min, lessThan, , , , tax]) => {
+ expectTaxUnder100KRange(FilingStatus.HOH, min, lessThan - 0.01, tax)
+ })
+
+ // Over $100,000
+ const amounts = [
+ [100000, 16569],
+ [164900, 32145],
+ [164901, 32145],
+ [209400, 46385],
+ [209401, 46385],
+ [523600, 156355],
+ [523601, 156355]
+ ]
+ amounts.forEach(([amount, tax]) => {
+ expectTax(FilingStatus.HOH, amount, tax)
+ })
+ })
+})